I read the most interesting article in the magazine New Scientist about the addictive quality (for some people) of what the article terms "junkie" food, i.e. food high in sugars, salt and fats. It's a long article, but worth reading in its entirety.
A number of studies have found interesting clues to ways some individuals respond to food in a manner very similar to drug addiction where the reward circuitry of the brain is highjacked. Also, certain foods (see above) are more "addictive".
I know a lot of folks scoff at studies like these, and claim that by publishing results like this, the scientists end up (somehow) letting people off the hook of personal responsibility. I don't see it that way - a person who wants to deny their own complicity in engaging in addictive behavior doesn't need a study to do it. I find that learning about these correlations make it easier for me to understand some of my own past behavior. It helps to hear that there is some evidence for those of us who feel we have a food addiction, that we probably do. What it means then, is if we want to change our behavior, we can't just go on a diet and hope that our willpower is enough; the problem has to be addressed in a way that also works with the addictive quality of our eating habits and the kinds of food we eat. I fully believe that at the beginning of my weight loss, I made a very clear cut decision to save my own life. I guess that sounds dramatic, maybe I should phrase it, "decision to choose health above remaining mired in unhealthy overeating".